“Though they can seem like a timeless truth, it was not until the 1970s that ‘human rights’ became a household term and a global rallying cry,” she says.

Dr Keys’ new book Reclaiming American Virtue: The Human Rights Revolution of the 1970s seeks to identify the impulse at the core of this “new moralism”.

Surprisingly, it locates the roots of the modern human rights movement in Americans’ traumatised psychological state after the Vietnam War.

“It is hard to overstate how deeply unsettling the war was for Americans, whose faith in their country’s benevolence was profoundly shaken by the war’s extraordinary brutality,” she says.

“Martin Luther King Jr. famously called the United States ‘the greatest purveyor of violence in the world’ and many observers around the globe agreed. At home, liberals in particular felt ashamed and guilty.

“The desire to assuage these feelings – not to atone for them but to sublimate them – led liberals to embrace human rights.”

Which bring us back to that naughty young child dobbing in a friend.

Dr Keys argues increasing moves by the US to shine a light on the wrongdoing of other nations may have been less about actually preventing atrocities, and more about creating a distraction from America’s own sense of national shame.

“As I see it, promoting international human rights was not a ‘natural’ response triggered by an epidemic of human rights abuses, or by a cool-headed rethinking of Cold War anti-communism.

“Instead it was a kind of sleight-of-hand, whereby Americans turned the spotlight away from America’s own recent history of violence to focus instead on brutal torture by nasty dictators in places like Chile and South Korea.

“Instead of reckoning with their own guilt, Americans made themselves feel better by pointing the finger at others.”

At the same time, however, another dynamic was at work. Dr Keys uncovers a largely forgotten conservative strand of human rights promotion, one that sowed the seeds for the neoconservative enthusiasm for human rights and democratisation that defined the George W. Bush era.

Indeed, it was the men and women who would don the neoconservative label a few years later who first introduced international human rights into mainstream American political vocabulary in the early 1970s.

“These conservatives found liberal guilt enraging. They rejected any effort to blame the United States,” Dr Keys notes.

“They grasped human rights as a tool to criticise the Soviet Union, and in particular to press for greater levels of Soviet Jewish emigration. Human rights was useful to conservatives because the concept restored moral stature to the United States and placed opprobrium squarely on the Soviet Union – effectively righting the moral balance that had been upset by the Vietnam War.”

Jimmy Carter, when he became president in 1977, made international human rights promotion one of the central pillars of U.S. foreign policy. His advisers told him human rights appealed to both liberals and conservatives, and could help heal the psychological damage the war had caused.

But Dr Keys believes Carter failed to reckon with the irreconcilable divergence between liberal and conservative visions of human rights, which prioritised very different rights and were aimed at very different targets.

“Though the new policy was hobbled by unresolved contradictions, including the tension between liberal and conservative visions of what human rights were, Carter gave the new mantra the full backing of a superpower and thereby almost single-handedly ensured the rise of human rights to its current status in the global moral imagination,” Dr Keys says.

Her explanation for the rise of human rights makes the arc of US foreign policy sentiment since the end of the Vietnam War more understandable.

Meantime, the liberal version of human rights similarly derived from a failure to reckon with the true costs of American interventionism in Vietnam.

The neocons who would plot the invasion of Iraq after the election of George W. Bush had first embraced the moralism of human rights as a rejection of guilt for the Vietnam War.

Human rights made renewed interventionism more thinkable, not less – which is why so many liberals could end up supporting Bush’s war for human rights.